The planar droplet sizing technique reveals a full 2-dimensional map of the Sauter Mean Diameter (D32) with Laser Imaging. This approach is complementary to measurements with Phase Doppler Interferometry (PDI).The D32-laser imaging technique measures relative droplet sizes in a plane, while PDI measures calibrated size-velocity distributions of individual droplets in a point.
The basic principle behind planar D32 measurements consists of recording two images from the spray, one with laser induced fluorescence (LIF) and simultaneously a corresponding one with direct light scattering (Mie).
While the LIF image represents the droplet’s volume, the Mie scattered light is basically proportional to the total droplet surface. The ratio of both is proportional to the definition of the Sauter Mean Diameter.